The present invention relates in general to an alarm device and in particular to an alarm device for signalling defective conditions in a motor vehicle having an internal combustion engine equipped with an electronic fuel metering control system.
From German publication No. DE-OS 31 09 638 a monitoring device is known which monitors an electronically controlled gas pedal in a motor vehicle. The prior art device uses a program memory for identifying correct or false address words whereby the individual bits of such address words are derived from test potentials detected at components of the electronic gas pedal controlling arrangement. The output of the program memory is applied to a warning device in the form of a signal generator which in the case of the detection of at least one erroneous test potential becomes activated and signals to the operator of the vehicle the occurrence of a possible hazard. If a defect occurs in the warning device itself however the error and the resulting risky condition remain undetected.
It is also generally known, at the occurrence of a defect in the regulating system of an internal combustion engine, to automatically reset to a zero position the setting mechanism which controls fuel metering whereby the zero position corresponds to an adjustment for dosing smaller amounts of fuel. In this manner in the case of a fault an uncontrolled or excessive power output of the IC engine and the resulting hazard for the operator of the vehicle, are avoided. Due to the reduced fuel metering the vehicle can operate only in the emergency mode of operation at which the power output is considerably reduced and subsequently the utility of the vehicle is considerably limited.